There are many types of dementia caused by different brain diseases. Dementia is the umbrella term for a number of neurological conditions, of which the major symptom includes a global decline in brain function. We now know dementia is a disease symptom, and not a normal part of aging. There are over 100 diseases that may cause dementia. The most common causes of dementia are:
- Alzheimer’s disease
- Vascular dementia
- Lewy body disease
- Fronto-temporal dementia (including Pick’s disease)
The boundaries between the different types are not necessarily distinct. Alzheimer’s disease and vascular dementia are responsible for up to 90% of cases of dementia.
Alzheimer’s disease is the most common form of dementia, affecting up to 70% of all people with dementia. It was first recorded in 1907 by Dr Alois Alzheimer. Alzheimer’s is a type of dementia that causes problems with memory, thinking and behavior. Symptoms usually develop slowly and get worse over time, becoming severe enough to interfere with daily tasks. Alzheimer’s disease can be either sporadic or familial. Sporadic Alzheimer’s disease can affect adults at any age, but usually occurs after age 65 and is the most common form of Alzhiemer’s disease. Familial Alzheimer’s disease is a very rare genetic condition, caused by a mutation in one of several genes. The presence of mutated genes means that the person will eventually develop Alzheimer’s disease, usually in their 40’s or 50’s.
How does Alzheimer’s disease progress?
The rate of progression of the disease varies from person to person. However, the disease does lead eventually to complete dependence and finally death, usually from another illness such as pneumonia. A person may live from three to twenty years with Alzheimer’s disease, with the average being seven to ten years.
Symptomes of Alzheimer’s disease
In the early stages the symptoms of Alzheimer’s disease can be very subtle. However, it often begins with lapses in memory and difficulty in finding the right words for everyday objects. Other symptoms may include:
- Persistent and frequent memory difficulties, especially of recent events
- Vagueness in everyday conversation
- Apparent loss of enthusiasm for previously enjoyed activities
- Taking longer to do routine tasks
- Forgetting well-known people or places
- Inability to process questions and instructions
- Deterioration of social skills
- Emotional unpredictability
Symptoms vary and the disease progresses at a different pace according to the individual and the areas of the brain affected.
A person’s abilities may fluctuate from day to day, or even within the one day, becoming worse in times of stress, fatigue or ill-health.
Vascular dementia is the second most common cause of dementia after Alzheimer’s disease. It is the broad term for dementia associated with problems of circulation of blood to the brain. There are a number of different types of Vascular dementia. Two of the most common are Multi-infarct dementia and Binswanger’s disease.
This is probably the most common form of Vascular dementia. Multi-infarct dementia is caused by a number of small strokes, called mini-strokes or Transient Ischaemic Attacks (TIA). The strokes cause damage to the cortex of the brain, the area associated with learning, memory and language. A person with Multiinfarct dementia is likely to have better insight in the early stages than people with Alzheimer’s disease, and parts of their personality may remain relatively intact for longer. Symptoms may include severe depression, mood swings and epilepsy.
Binswanger’s disease (also known as Subcortical vascular dementia)
This was thought to be rare, but is now being reassessed, and may in fact be relatively common. As with other Vascular dementias, it is associated with stroke-related changes. It is the “white matter” deep within the brain that is affected. It is caused by high blood pressure, thickening of the arteries and inadequate blood flow. Symptoms often include slowness and lethargy, difficulty walking, emotional ups and downs and lack of bladder control early in the course of the disease. Most people with Binswanger’s disease have, or have had, high blood pressure. One single large stroke can sometimes cause Vascular dementia depending on the size and location of the stroke. Risk factors that make strokes more likely to lead to Vascular dementia include:
- Untreated high blood pressure (hypertension)
- Atrial fibrillation
- Other irregular heart rhythms which raise the risk of clots and atherosclerosis (fatty deposits in blood vessels) which causes damage to the arteries of the brain.
Who gets vascular dementia?
Anyone can be affected by Vascular dementia, but several factors increase the risk. These include:
- High blood pressure
- High cholesterol
- History of mild warning strokes
- Evidence of disease in arteries elsewhere
- Heart rhythm abnormalities
Vascular dementia is slightly more common in men than women.
How is Vascular dementia diagnosed?
Vascular dementia is usually diagnosed through neurological examination and brain scanning techniques such as computerised tomography (CT) or a magnetic resonance imaging (MRI) test. However, as is the case with Alzheimer’s disease, a definite diagnosis of Vascular dementia can only be made by examining the brain after death. Vascular dementia can be very difficult to distinguish from other forms of dementia. Some people have both Alzheimer’s disease and Vascular dementia.
How does vascular dementia progress?
Vascular dementia usually progresses gradually in a step-wise fashion in which a person’s abilities deteriorate after a stroke, and then stabilise until the next stroke. If further strokes do not occur, the abilities of people with Vascular dementia may not continue to decline, or in some cases, may improve. However, these improvements may not last. Sometimes the steps are so small that the decline appears gradual. On average though, people with Vascular dementia decline more rapidly than people with Alzheimer’s disease. Often they die from a heart attack or major stroke.
Is there treatment available?
While no treatment can reverse damage that has already been done, treatment to prevent additional strokes is very important. To prevent strokes, medicines to control high blood pressure, high cholesterol, heart disease and diabetes can be prescribed. A healthy diet, exercise and avoidance of smoking and excessive alcohol also lessen the risk of further strokes. Sometimes aspirin or other drugs are prescribed to prevent clots from forming in the small blood vessels. Drugs can also be prescribed to relieve restlessness or depression or to help the person with dementia to sleep better. In some cases surgery known as carotid endarterectomy may be recommended to remove blockage in the carotid artery, the main blood vessel to the brain. Recent research suggests that cholinesterase inhibitor medications such as Donepezil (Aricept) and Galantamine (Reminyl), which are helpful for some people with Alzheimer’s disease, may also be of some benefit to some people with Vascular dementia. However, the evidence is not yet as clear or compelling as that for the use of these medications with Alzheimer’s disease. Support is available for the person with Vascular dementia, their families and carers. This support can make a positive difference to managing the condition. Alzheimer’s Australia provides support, information, education and counselling for people affected by dementia. Up-to-date information about drug treatments is also available from Alzheimer’s Australia.
Lewy body disease
Lewy body disease is a common form of dementia, sharing many similarities with Alzheimer’s disease. Lewy body disease is caused by the degeneration and death of nerve cells in the brain. The name comes from the presence of abnormal spherical structures, called Lewy bodies, which develop inside nerve cells. It is thought that these may contribute to the death of the brain cells. They are named after the doctor who first wrote about them. It is sometimes referred to as Diffuse Lewy body disease.
What is the cause?
At present there is no known cause of Lewy body disease, and no known risk factors have been identified. There is no evidence that it is an inherited disease.
How is lewy body disease diagnosed?
This type of dementia is diagnosed by taking a careful history of the pattern of symptoms, and by excluding other possible causes such as Vascular dementia and Alzheimer’s disease. A brain scan may reveal brain degeneration, but the Lewy bodies can only be identified by examination of brain tissue after death. Lewy body disease is similar to Alzheimer’s disease in many ways, and in the past it has sometimes been difficult to distinguish the two. It has only recently been accepted as a disease in its own right. It can occur by itself or together with Alzheimer’s disease and/or Vascular dementia. It may be hard to distinguish Lewy body disease from Parkinson’s disease, and some people with Parkinson’s disease develop a dementia which is similar to that seen in Lewy body disease.
What are the symptoms?
The symptoms of dementia with Lewy body disease include:
- Difficulty with concentration and attention
- Extreme confusion
- Difficulties judging distances, often resulting in falls.
There are also three cardinal symptoms, two of which must be present in order to make the diagnosis:
- Visual hallucinations
- Parkinsonism (tremors and stiffness similar to that seen in Parkinson’s disease)
- Fluctuation in mental state so that the person may be lucid and clear at one time and confused, disoriented and bewildered at other times. Typically this fluctuation occurs over a period of hours or even minutes and is not due to any underlying acute physical illness.
Some people who have Lewy body disease may also experience delusions and/or depression.
Who gets lewy body disease?
Both men and women can develop this disease, although it is more common in men.
How does lewy body disease progress?
Lewy body disease differs from Alzheimer’s disease in that the progression of the disease is usually more rapid. However, like Alzheimer’s disease it is a degenerative condition, eventually leading to complete dependence. Death is usually a result of another illness, such as pneumonia or an infection. The average lifespan after the onset of symptoms is about seven years.
Is there treatment available?
At present there is no cure for Lewy body disease. Symptoms such as depression and disturbing hallucinations can usually be reduced by medication. However, medications to relieve hallucinations may increase muscle tremors and stiffness. Conversely, anti-Parkinson drugs may make hallucinations worse. Emerging evidence suggests that cholinesterase inhibitor drugs may be quite helpful for some people with this condition. People with this form of dementia are very sensitive to the side effects of neuroleptic drugs such as antipsychotic dications. It is essential all medications are supervised by a specialist to avoid these severe side effects.
Fronto Temporal dementia (including Pick’s disease)
This is the name given to dementia when there is degeneration in one or both of the frontal or temporal lobes of the brain.
The right and left frontal lobes govern mood, behaviour, judgement and self-control. Damage leads to alterations in personality and behaviour, changes in the way a person feels and expresses emotion and loss of judgement.
The right and left temporal lobes are involved in the organisation of sensory input such as what you hear or see. Damage may lead to difficulty placing words or pictures into categories. There is considerable difference in FTLD symptoms depending on which parts of the frontal and temporal lobes are affected. The three main subtypes or variants are:
- Fronto Temporal Dementia (FTD) is the most common subtype or Frontal Variant. It is mainly a disorder of behaviour. People with FTD may be disinhibited or apathetic
- Progressive non-Fluent Aphasia (PA), which was formerly known as Primary Progressive Aphasia (PPA). People with PA may lose the ability to speak or may begin to speak gibberish
- Semantic Dementia (SD) (Progressive Fluent Aphasia) is also known as the Temporal Variant. People with SD may lose the meaning of words and also may become preoccupied with a single activity Although people with FTLD may be assessed as one of the three subtypes above, the disease will progress and people with FTLD are likely to develop signs and symptoms that are a mixture of two or three subtypes.
FTLD causes progressive and irreversible decline in a person’s abilities over a number of years.
What is pick’s disease?
Pick’s disease is a type of Fronto Temporal Lobar Degeneration, named after the German neurologist who first described it in 1892. Pick’s disease affects the frontal lobes, but in some cases can affect the temporal lobe of the brain. If the temporal lobe is damaged, memory is more likely to be affected.
Who gets frontal lobe dementia?
Frontal lobe dementia, including Pick’s disease, can affect both men and women. Although it can affect people at any age, it usually begins between 40 to 65 years of age.
What causes fronto temporal lobar degeneration?
About 50% of people with FTLD have a family history of the disease. Those who inherit it seem to have a mutation in the tau protein gene on chromosome 17, leading to abnormal tau protein being produced. Other risk factors are less well known.
Is there treatment available?
Unfortunately, there is not yet a cure for FTLD, nor is there currently any treatment. However secondary symptoms, such as depression, can be helped by medication. Management lies in developing coping strategies. Knowing more about the disease and why the person is behaving as they are can in itself be an effective means of helping people to cope with the disease. Family members and carers can develop their own coping strategies, such as avoiding confrontation and working around obsessions, rather than trying to change the behaviour of those affected.
What are the symptoms?
Early symptoms can affect behaviour, and sometimes language. People may show a change in their character and in their social behaviour. For example, they may show insensitivity when they have previously been very considerate of others. A person with FTLD may become obsessive and repeat the same action over and over again.
Language problems often occur early in the disease and may range from limited speech to total loss of speech. Repeating phrases over and over, or echoing what others have said are also common symptoms. Instead of being able to find the right word to describe an object, a person with FTLD may give a description of it instead. For instance, instead of naming a watch, the person may refer to something you tell the time with.
How is fronto temporal lobar degeneration diagnosed?
There are several techniques such as brain scans, an electroencephalogram (EEG) and neuropsychological tests which can be used to make a probable diagnosis. These tests can help to determine whether the dementia is likely to be FTLD, or another disorder, such as Alzheimer’s disease. Like Alzheimer’s disease however, the diagnosis can only be confirmed after death by examination of the brain tissue.
How does the disease progress?
The course of FTLD is one of inevitable progressive deterioration. From the onset of the disease, life expectancy is two to fifteen years, with an average of six to twelve years. Death usually comes from another illness such as infection.